but I'm a firm believer in shot gun tactics ask everyone and you’ll get an answer
And, "The Lord helps those who help themselves."
It's always a good idea to compare mods and find out what files they have in common before using them. Especially when modifying a live shop.
Some use winmerge, beyondcompare, or (paid) ultracompare to make sure the commonalities are found and dealt with properly.
Using one of those, you'll find that the add pages mod uses a modified includes/languages/custom/english.php as does the events mod. The english.php file holds defines specific to the English language. The variables (in ALL_CAPS format) are set so that they can be called when needed and only need to be defined once. When you see "BOX_INFORMATION_EVENTS" or something similar, it tells you that a define has failed or doesn't exist.
The english.php file provided with the add pages mod is an older version and has an addition to the footer that is (IMHO) stretching the definition of Designed By. It also modifies a core file - includes/filenames.php. This means that an upgrade will wipe out the changes and break the mod.
I would first take the english.php file from the events mod and do the following:
Around line 148, replace
// information box text in sideboxes/more_information.php - were TUTORIAL_
define('BOX_HEADING_MORE_INFORMATION', 'More Information');
define('BOX_INFORMATION_PAGE_2', 'Page 2');
define('BOX_INFORMATION_PAGE_3', 'Page 3');
define('BOX_INFORMATION_PAGE_4', 'Page 4');
with
// information box text in sideboxes/more_information.php - were TUTORIAL_
define('BOX_HEADING_MORE_INFORMATION', 'More Information');
define('BOX_INFORMATION_PAGE_2', 'Page 2');
define('BOX_INFORMATION_PAGE_3', 'Page 3');
define('BOX_INFORMATION_PAGE_4', 'Page 4');
define('BOX_INFORMATION_PAGE_5', 'Page 5');
define('BOX_INFORMATION_PAGE_6', 'Page 6');
define('BOX_INFORMATION_PAGE_7', 'Page 7');
Then, take the includes/extra_datafiles/extra_pages_filenames.php included in the events mod and replace
<?php
// $Id: extra_pages_filenames.php 2008-12-31 08:07:26Z dbltoe $
// define the extra page filenames
define('FILENAME_DEFINE_EVENTS', 'define_events');
define('FILENAME_EVENTS', 'events');
?
with
<?php
// $Id: extra_pages_filenames.php 2008-12-31 08:07:26Z dbltoe $
// define the extra page filenames
define('FILENAME_DEFINE_EVENTS', 'define_events');
define('FILENAME_EVENTS', 'events');
define('FILENAME_DEFINE_PAGE_5', 'define_page_5');
define('FILENAME_DEFINE_PAGE_6', 'define_page_6');
define('FILENAME_DEFINE_PAGE_7', 'define_page_7');
?
Then replace the includes/filenames.php that came with the add pages mod with the original includes/filenames.php that came with your version of Zen Cart.
Doing both these things will allow the mods to work together and not be broken by a future upgrade.